Field
The present invention relates generally to input and output power compensation for pre-distorted transmit signals.
Background
Electronic amplifiers are used for increasing the power and/or amplitude of various electronic signals. Most electronic amplifiers operate by using power from a power supply, and controlling an output signal to match the shape of an input signal, while providing a higher amplitude signal. One widely used type of electronic amplifier is a power amplifier, which is a versatile device used in various applications to meet design requirements for signal conditioning, special transfer functions, analog instrumentation, and analog computation, among others. Power amplifiers are often used in wireless applications, and may employ radio-frequency (RF) amplifier designs for use in the RF range of the electromagnetic spectrum. An RF power amplifier is a type of electronic amplifier used to convert a low-power RF signal into a signal of significant power, typically for driving an antenna of a transmitter. RF power amplifiers are oftentimes used to increase the range of a wireless communication system by increasing the output power of a transmitter.
Power amplifiers typically do not behave in a linear manner. More particularly, power amplifier distortion may compress or may expand an output signal swing of a power amplifier. Signal detectors receiving and decoding the amplified signals typically do not operate in such a non-linear fashion. Therefore, it is usually necessary to linearize an output of a power amplifier. One approach to such linearization is digital pre-distortion (DPD). Digital pre-distortion may be calibrated and used with power amplifiers to invert power amplifier distortion characteristics by expanding compression regions and compressing expansion regions of power amplifier characteristics. However, as will be appreciated by a person having ordinary skill in the art, over frequency, temperature, and/or voltage standing wave ratio (VSWR), characteristics of a power amplifier may change. As a result, performance of a transmitter including a power amplifier may degrade significantly because the calibrated DPD no longer aligns with the nonlinearity of the power amplifier.
A need exists for embodiments related to enhancing a process of calibrating signal power levels of a power amplifier within a system including DPD.